Re: [PATCH 1/2] spi/pl022: timeout on polled transfer

[Linus Walleij <linus.walleij@linaro.org>]

On Thu, May 19, 2011 at 2:44 PM, Wolfram Sang <w.sang@pengutronix.de> wrote:

> Hi,
>
>> -             /* FIXME: insert a timeout so we don't hang here indefinitely */
>> -             while (pl022->tx < pl022->tx_end || pl022->rx < pl022->rx_end)
>> +
>> +             timeout = jiffies + msecs_to_jiffies(SPI_POLLING_TIMEOUT);
>
> Won't you miss the transfer if you get interrupted here longer than
> SPI_POLLING_TIMEOUT?

Yeah... preempted for a second hm.

>> +             while (pl022->tx < pl022->tx_end || pl022->rx < pl022->rx_end) {
>> +                     if (time_after(jiffies, timeout)) {
>> +                             dev_warn(&pl022->adev->dev,
>> +                             "%s: timeout!\n", __func__);
>> +                             message->state = STATE_ERROR;
>> +                             goto out;
>> +                     }
>>                       readwriter(pl022);
>> +             }

What about we move readerwriter() above if (time_after...) then it atleast
gets one chance to run even if we're preempted for 10 seconds.

Any other design patterns that'd be better?

Yours,
Linus Walleij